Emacs in particular I suffer so much from basically guessing what needs to be escaped or not. I know `rx` exists[0] as an alternative but it's not really fun to use.
Even beyond the regex syntax itself, you often also start running into encoding problems when trying to actually use them. Typing the regex in a shell? Make sure to esacpe stuff properly. Regex in Python? Make sure it's a raw string. Etc etc etc
It's a modern miracle we're at least within rhyming distance of how to write regexes in most tools.
[0]: https://www.gnu.org/software/emacs/manual/html_node/elisp/Rx...
Even more fun writing python that generates shell scripts that contain regex, and other nested-different-escaping scenarios.
Grasping at straws, it's kinda convenient that ( and ) match literally if the text being searched is Elisp code!